Seggregation of one year data day wise (Day of year)

I have a matrix which consist of 10 columns and few thousands of rows ...

First column year...

Second column Month...

Third Column Day... [1,2,3...30 and 31 for alternate months]

Fourth , Fifth, Sixth Column ... Hour, Min, Sec.. and so on

Last four columns are some other parameters of my interest...

Now I want to segregate it day wise of a year, as Day of Year (DOY) 1,2 3....365 days of a year..

separate Mat files day wise or a structure consist of all days... 1 to 365.. Daywise(1 to 365).data consist of all the 10 columns but day wise rows

Please help me in this regard

Thanks in advance